The information required to write a USB device driver is plentiful, if you have the time and patience to find it. This paper demonstrates, through the use of a practical example, a simple approach to writing a WinCE 5.0 USB device driver. The example includes the basic structure and requirements for implementing a device driver for a commercially available USB fingerprint sensor. The approach details how to write a WinCE stream driver, how to communicate via the USB bus, how to install the driver on a platform, and how to ensure proper communications between the application and the device driver.